xref: /freebsd/usr.bin/gprof/elf.c (revision 2be1a816b9ff69588e55be0a84cbe2a31efc0f2f)
1 /*-
2  * Copyright (c) 1983, 1993
3  *	The Regents of the University of California.  All rights reserved.
4  *
5  * Redistribution and use in source and binary forms, with or without
6  * modification, are permitted provided that the following conditions
7  * are met:
8  * 1. Redistributions of source code must retain the above copyright
9  *    notice, this list of conditions and the following disclaimer.
10  * 2. Redistributions in binary form must reproduce the above copyright
11  *    notice, this list of conditions and the following disclaimer in the
12  *    documentation and/or other materials provided with the distribution.
13  * 3. All advertising materials mentioning features or use of this software
14  *    must display the following acknowledgement:
15  *	This product includes software developed by the University of
16  *	California, Berkeley and its contributors.
17  * 4. Neither the name of the University nor the names of its contributors
18  *    may be used to endorse or promote products derived from this software
19  *    without specific prior written permission.
20  *
21  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
22  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
23  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
24  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
25  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
26  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
27  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
28  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
29  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
30  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
31  * SUCH DAMAGE.
32  */
33 
34 #if 0
35 /* From: */
36 #ifndef lint
37 static char sccsid[] = "@(#)gprof.c	8.1 (Berkeley) 6/6/93";
38 #endif /* not lint */
39 #endif
40 
41 #include <sys/cdefs.h>
42 __FBSDID("$FreeBSD$");
43 
44 #include <sys/types.h>
45 #include <sys/mman.h>
46 #include <sys/stat.h>
47 #include <machine/elf.h>
48 
49 #include <err.h>
50 #include <fcntl.h>
51 #include <string.h>
52 #include <unistd.h>
53 
54 #include "gprof.h"
55 
56 static bool wantsym(const Elf_Sym *, const char *);
57 
58 /* Things which get -E excluded by default. */
59 static char	*excludes[] = { ".mcount", "_mcleanup", NULL };
60 
61 int
62 elf_getnfile(const char *filename, char ***defaultEs)
63 {
64     int fd;
65     Elf_Ehdr h;
66     struct stat s;
67     void *mapbase;
68     const char *base;
69     const Elf_Shdr *shdrs;
70     const Elf_Shdr *sh_symtab;
71     const Elf_Shdr *sh_strtab;
72     const char *strtab;
73     const Elf_Sym *symtab;
74     int symtabct;
75     int i;
76 
77     if ((fd = open(filename, O_RDONLY)) == -1)
78 	err(1, "%s", filename);
79     if (read(fd, &h, sizeof h) != sizeof h || !IS_ELF(h)) {
80 	close(fd);
81 	return -1;
82     }
83     if (fstat(fd, &s) == -1)
84 	err(1, "cannot fstat %s", filename);
85     if ((mapbase = mmap(0, s.st_size, PROT_READ, MAP_SHARED, fd, 0)) ==
86       MAP_FAILED)
87 	err(1, "cannot mmap %s", filename);
88     close(fd);
89 
90     base = (const char *)mapbase;
91     shdrs = (const Elf_Shdr *)(base + h.e_shoff);
92 
93     /* Find the symbol table and associated string table section. */
94     for (i = 1;  i < h.e_shnum;  i++)
95 	if (shdrs[i].sh_type == SHT_SYMTAB)
96 	    break;
97     if (i == h.e_shnum)
98 	errx(1, "%s has no symbol table", filename);
99     sh_symtab = &shdrs[i];
100     sh_strtab = &shdrs[sh_symtab->sh_link];
101 
102     symtab = (const Elf_Sym *)(base + sh_symtab->sh_offset);
103     symtabct = sh_symtab->sh_size / sh_symtab->sh_entsize;
104     strtab = (const char *)(base + sh_strtab->sh_offset);
105 
106     /* Count the symbols that we're interested in. */
107     nname = 0;
108     for (i = 1;  i < symtabct;  i++)
109 	if (wantsym(&symtab[i], strtab))
110 	    nname++;
111 
112     /* Allocate memory for them, plus a terminating entry. */
113     if ((nl = (nltype *)calloc(nname + 1, sizeof(nltype))) == NULL)
114 	errx(1, "insufficient memory for symbol table");
115 
116     /* Read them in. */
117     npe = nl;
118     for (i = 1;  i < symtabct;  i++) {
119 	const Elf_Sym *sym = &symtab[i];
120 
121 	if (wantsym(sym, strtab)) {
122 	    npe->value = sym->st_value;
123 	    npe->name = strtab + sym->st_name;
124 	    npe++;
125 	}
126     }
127     npe->value = -1;
128 
129     *defaultEs = excludes;
130     return 0;
131 }
132 
133 static bool
134 wantsym(const Elf_Sym *sym, const char *strtab)
135 {
136     int type;
137     int bind;
138 
139     type = ELF_ST_TYPE(sym->st_info);
140     bind = ELF_ST_BIND(sym->st_info);
141 
142     if (type != STT_FUNC ||
143       (aflag && bind == STB_LOCAL) ||
144       (uflag && strchr(strtab + sym->st_name, '.') != NULL))
145 	return 0;
146 
147     return 1;
148 }
149